The invention relates to improvements to check valves having elastomeric hinges. Check valves are used in various applications to permit flow in one direction in a pipe but restrict flow in the opposite direction. Check valves are available in various designs but essentially comprise a valve body that houses a check valve assembly. The check valve assembly includes at least one valve plate that blocks return flow when the valve is in the closed position. An elastomeric hinge check valve is a type of check valve in which the check valve assembly includes an elastomeric hinge that typically comprises an elastomeric member and a hinge member around which the elastomeric member can bend. The elastomeric member is usually secured to the hinge member. Various designs of elastomeric check valves include, among other things, springs or other mechanical devices to bias the check valve assembly in a closed position.
The elastomeric member is typically sized to fit into a valve body such that when the check valve is in the closed position, the elastomeric member forms a seal against the inner dimension of the valve body. Check valves assemblies are sold either enclosed in a valve body for immediate insertion into a conduit system or as internal mechanisms for later installation in valve bodies.
During the normal course of operation of a check valve, the check valve assembly, housed in a valve body, is installed in a conduit system that conveys a material that is required to flow in one direction. This could be a sewer system, a drinking water system, a manufacturing facility, a food processing facility, a natural gas line, etc. Check valves are installed at locations in conduit systems where, for whatever reason, material may tend to flow in the opposite direction from what is required. For example, in a drinking water system in which a water pump is used to pump water uphill, if the pump is shut off, the water in the pipes will tend to run downhill, or backflow, to the pump. A check valve would be installed after the pump to prevent unnecessary wear or damage to the pump from this backflow coming in the wrong direction. The direction that the flow of material is required to go is called the downstream direction. The direction that the flow is required to come from is called the upstream direction. A variety of types of check valves could be installed in conduit systems to prevent backflow in the upstream direction.
One of the weak points of elastomeric hinge check valves is the elastomeric member itself. The elastomeric member is typically made of a flexible rubber or other elastomeric material that can bend around the hinge member. Over the course of its operation the elastomer will tend to stretch or will be abraded due to contact against the edge portions of the check valve components or due to erosion caused by material flowing in a conduit system in which the check valve is installed. These stresses can stretch and cut the elastomeric member making the valves ineffective or less effective and reduce the life expectancy of the valve.